Today, electronic devices are often networkable devices, That is to say, such devices may often be incorporated into wired networks, such as Ethernet, or wireless networks, for example cellular networks, ZigBee networks, Bluetooth networks and Wi-Fi networks. Another example of a network of devices is an in-vehicle network. Networkable devices may transmit a large amount of data to each other over wired or wireless communication channels. In order to protect the transmitted data, the data are often encrypted. For example, they may be encrypted by performing a cryptographic algorithm which takes a cryptographic key and said data as inputs, or, in other words, the data may be encrypted with the cryptographic key. An example of such a cryptographic algorithm is the so-called Advanced Encryption Standard (AES) algorithm. In case of symmetric-key cryptographic algorithms, the cryptographic key is a secret key which is shared between a source node and a destination node involved in a data transmission, and which should preferably have a limited lifetime. Therefore, so-called session keys are often generated. Session keys can only be used during a specific session of short duration, in order to prevent replay attacks.